From Altai article: "Among the people who may have emerged from the Altai region are the predecessors of the first Native Americans. Roughly 20-25,000 years ago, these prehistoric humans carried their Asian genetic lineages up into the far reaches of Siberia and eventually across the then-exposed Bering land mass into the Americas."

Since the Australasians didn't pass through the Beringea corridor they apparently arrived by boat in South America (BTW on currents that run east at that latitude). Can't have that, Spice!